Opinions on managing pages/numbers files between windows and iPad?

Hello all My wife received an iPad for christmas and she wants to start using it as her main machine as all she does is e-mail, some web browsing and word/excel documents. I am trying to figure out the best way to keep her documents synched between her windows 7 machine and pages/numbers. She won't be going back to windows much but if she does, she would like all her docs up to date between both machines. I looked at dropbox and google drive so far. I saw that google has an open in option so that should work although after she saves a document, she'd have to go back in to google and add the updated version of any files manually. Does anyone know of an easier way? It would be great if I could get this working since she really enjoys using the iPad and would love to use it for as many tasks as possible. No random crashes in the middle of something as with jaws and the bluetooth keyboard support is spectacular as well.